So you can breath less and get more by breathing through the nose. - James Nestor

I went to Greece to write a story on ... When most people go underwater... they bail out at ten feet... ears screaming. The freedivers told me they'd previously been "most people." ...To freedive, they said, all anyone had to do was master the art of breathing.

Back in the 60s... John Lilly had a lab... dedicated to solving the dolphin communication problem...

Truebridge just dove thirty stories... all on one lungfull of air... The pressure... is more than ten times that at the surface, strong enough to crush a Coke can. At thirty feet. the lungs collapse to hald their normal size; at three hundred feet they shrink to the size of two baseballs. ...The dives don't look forced... as if they all really belong down there. As if we all do.